This invention relates to a vehicle air exchange system, i.e., a ventilating system, and more particularly, to such a system which operates economically and efficiently by providing the necessary amount of ventilation depending upon the number of passengers in a vehicle. The present invention is an adjunct to the heating and air conditioning systems heretofore used in connection with such vehicles.
There is a need for controlling the amount of fresh air provided to an electrically operated vehicle such as a people mover vehicle, train, subway car or the like. The American Society of Heating, Refrigerating and Air Conditioning Engineers has established ventilation standards for acceptable indoor air quality (ASHRAE standard 62-1981 suggests 8.5 cubic meters per hour, per person).
Prior to the present invention, ventilation of people mover vehicles was typically based upon the maximum rated passenger load. Of course, since the vehicles were not always fully occupied, much of the energy used to ventilate the vehicle was wasted because much of the ventilation was unnecessary. Furthermore, when considered in conjunction with heating and air conditioning, there was an even more substantial waste of energy since fresh air or outside air was being brought into the vehicle and thereafter unnecessarily heated or cooled.